The most conventional way for sensing compression loading is disclosed by U.S. Pat. Nos. 2,873,341 Kutsay and 3,201,977 Kutsay wherein strain gauges are secured directly to a member whose compression loading is to be sensed. Usually the strain gauges are secured by potting, as disclosed by the Kutsay patents, internally within a hole in the member which often takes the form of a threaded bolt. However, prior art transducers have also included strain gauges secured externally to outer surfaces of a bolt to sense loading.
Another transducer for sensing compression loading is disclosed by the U.S. Pat. No. 2,925,576 of Wakeland et al wherein a round shaft has a strain gauge secured thereto intermediate a cone shaped inner end of the transducer and a threaded outer portion thereof that is received by the threaded outer end of a hole in a bolt. One problem with this type of transducer is that the conical inner end thereof does not seat during the threading of the outer end thereof into the bolt hole. As such, it is difficult to obtain accurate readings. Furthermore, the round intermediate portion of the transducer on which the strain gauges are mounted does not lend itself to accurate readings.
Other strain gauge transducers and the like are disclosed by U.S. Pat. Nos.: 2,393,714 Simmons, Jr.; 2,600,029 Stone; 2,747,454 Bowersett; 3,132,319 Brooks, Jr.; 3,212,325 Katz et al; 3,905,356 Fletcher et al; 4,042,049 Reichow et al; 4,127,788 Daugherty; 4,200,855 Gilcher; 4,203,318 Yorgiadis; 4,280,363 Johansson; and 4,429,579 Wilhelm.